Taps & Dies Question

I just bought this set of taps and dies and dont know anything about this type of die handle, can anyone help on use of them, and what are they called,and are they any good, thought they were cheap at £15

Edited By john dakin on 14/05/2017 18:32:00

They are very good as you can adjust the dies over quite a range. To cut a standard size thread, set them slightly oversize on a standard bolt then cut the thread and try a nut on it, if it is too tight, make an adjustment and take a second cut.

Great, thanks for the information

The actual cutters are called Coventry Die Heads and come in matched and numbered pairs, make sure they are both of a pair and the right way up.

I have a very big one of these and just two mismatched die heads - ho hum (but it only cost me 560p at a boot sale).

Neil

Never heard 'em called that before; definitely not what I thought a Coventry Diehead looked like.

Here's an interesting quote from a book I have on screw threads:

"The old-fashioned stock holding a pair of dies fed together by a screw has been largely supplanted by the more modern types, which have been dealt with, but it is a strong tool adapted to hard working, and variations in fit are easily obtained."

The book, written by F. J. Camm, was published in July 1942.

Andrew

Coventry die heads shown here :- **LINK**

(In the middle of the page)

Norman

Edited By NJH on 14/05/2017 22:09:03

One advantage of the two-part die is that you can slide it part way down the rod and start with a light cut, which reduces the risk of a drunken thread.

Geo.

And if you have a bolt with a damaged thread at the beginning you can slide the dies past it and work backwards.

John

They are certainly not Coventry die heads. Dies where probably made like that before Coventry die heads where invented. My father had a set and as I recall the taps and dies had a thread of their own ie neither Whit nor BSF possibly pre 1900

Roy

Must be challenging to manufacture - made in one piece as a pair then separated perhaps?

One advantage of the type of dies shown is when working on proper English motor bicycles or cycles. Any damage to the cycle-thread components needed only one set of dies - 26tpi, unless you were very unlucky.

Regards, Tim

At last count I had eight Coventry dieheads of assorted sizes. I use the smaller ones mainly on the repetition lathe. Rather than clutter up this thread I'll post a picture of a less common diehead to see who knows what it is for.

What puzzles me about the original tap & die set is that the diestocks, dies and box seem nicely made. But the taps seem to be black? Which indicates to me cheap carbon steel.

It would be useful to know what thread sizes are covered.

Andrew

What is the proper name for that type of cutter? My Newnes Engineer's Reference Book calls the usual type Round or Bottom dies. It mentions Spring and Prong dies 'capable of fine adjustment' but doesn't describe them. Could John's picture be of Prong dies or are they something else again?

Dave

Tom Senior 1939 catalogue calls them "Angle Pattern Stocks & Dies" but this name doesn't really address their two part construction.

They are shown alongside the more usual "Moorite" split circular dies.

It seems to me that the two part construction if well done would be superior in use to the split circular.

Edited By ega on 15/05/2017 11:22:36

In my set The dies and taps are carbon steel.

Ian S C

Thanks to everyone for your input and information, its good to know about this